Initial Studies of Holmium:YAG Laser Creation of Spinal Defects in Fetal Rabbits: Model for Urologic Effects of Myelomeningocele

Calvano, Christopher J.; Reddy, Pramod; Moran, Michael E.; Boyle, Karen E.; Housley, H. Tamiko; Jennings, Russell W.; Harrison, Michael R.; Mandell, James

doi:10.1089/end.1998.12.199

Cited by 7 publications

(12 citation statements)

References 30 publications

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“…The authors proposed the "two-hint hypothesis" for the mechanism of paralysis: a congenital myelodysplasia complicated by an intrauterine spinal cord injury. The same results were found in pigs and other models like the rabbit since then 5,21,22 . In these studies there was no time interval from the creation of the defect to its correction, so the use of a larger animal model, to permit a prolonged period in utero after surgical manipulation was needed, before extrapolation of these findings to humans.…”

Section: Discussionsupporting

confidence: 82%

Simplified correction of a meningomyelocele-like defect in the ovine fetus

Abou-Jamra¹,

Valente

Araújo³

et al. 2009

Acta Cir. Bras.

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Purpose: To develop a simplified technique for antenatal correction of a meningomyelocele -like defect in fetal sheep to allow direct skin closure. Methods: A spinal defect was surgically created at 75 days of gestation in the fetuses of 36 pregnant sheep, 23 survived the surgery. At 102 days gestation, the defect was corrected in 14 cases (9 were left untreated). Skin surrounding the defect was dissected below the dermis to permit its edges to be approximated and sutured, without interposing any material to its edges. An interface material intended to protect the neural tissue from skin adhesion was used and the skin defect was completely closed over it. Pregnancy was allowed to continue up to 138 days gestation, the fetuses were submitted to macroscopic and microscopic analysis. Results: The defect was successfully corrected in 90.9% in the experimental group, and spontaneous closure occurred in 22.3% in the control group (p < 0.05). The survival rate after the creation and correction of the defect was 63.4% and 78% respectively. Conclusion: This simplified technique was successful in the correction a meningomyelocele-like defect, in the fetal sheep. Key words: Surgery. Fetal Therapies. Meningomyelocele. Spinal Dysraphism. Disease Models, Animal. Sheep. RESUMOObjetivo: Desenvolver uma técnica simplificada de correção pré-natal de defeito semelhante à mielomeningocele em fetos de ovelha permitindo um fechamento direto da pele. Métodos: Um defeito espinhal foi cirurgicamente criado com 75 dias de gestação, em 36 fetos de ovelha, 23 sobreviveram à cirurgia. Após 102 dias de gestação, o defeito foi corrigido em 14 casos (9 não foram tratados). A pele em volta do defeito foi dissecada abaixo da derme para permitir a aproximação direta das bordas através de sutura, sem a interposição de nenhum material entre a pele. Um material de interface foi colocado entre o tecido neural exposto e a pele, com o objetivo de evitar a adesão da medula à pele, que foi completamente fechada sobre o defeito. A gravidez foi mantida até 138 dias, os fetos foram submetidos a análises macroscópicas e microscópicas. Resultados: O defeito foi corrigido em 90.9% no grupo experimental, e o fechamento espontâneo ocorreu em 22.3% no grupo controle (p < 0.05). A taxa de sobrevivência após a criação do defeito e posteriormente a sua correção foi de 63,4% e 78%, respectivamente. Conclusão: Esta técnica simplificada teve sucesso na correção do defeito semelhante à mielomeningocele em feto de ovelha. Descritores: Cirurgia. Terapias Fetais. Meningomielocele. Disrafismo Espinal. Modelos Animais de Doenças. Ovinos.

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Section: Discussionsupporting

confidence: 82%

Simplified correction of a meningomyelocele-like defect in the ovine fetus

Abou-Jamra¹,

Valente

Araújo³

et al. 2009

Acta Cir. Bras.

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“…Previous studies on the creation of a myelomeningocele-like defect in the fetal rabbit reported a fetal death rate varying from 40 [12] to 50% [11], while we found 26% in our series. Although the small numbers on all studies do not permit a statistically significant difference to be demonstrated, this modified technique was found to be a valid alternative method to produce the defect, perhaps safer than the previous ones described.…”

Section: Discussioncontrasting

confidence: 55%

“…When comparing the studies, we would also have to take into account the gestational age at fetal operation, since we expect lower ages to be associated with an increased mortality rate [13]. Both studies [11,12] operated fetuses on days 22-23 and we did it on day 23, so in this regard the studies could be compared. Fig.…”

Section: Discussionmentioning

confidence: 99%

“…Despite this, the rabbit was only recently established as a model for the surgical creation of the defect [11,12] and, so far, it has not yet been established as a model for its correction. With this objective in mind, we started a protocol to study the correction of a myelomeningocele-like defect using the technique described by Calvano et al [11] and subsequently modified by Housley et al [12] to produce it.…”

Section: Introductionmentioning

confidence: 99%

“…With this objective in mind, we started a protocol to study the correction of a myelomeningocele-like defect using the technique described by Calvano et al [11] and subsequently modified by Housley et al [12] to produce it. During our pilot study we needed to modify their technique and we intend to describe these modifications in the present study.…”

Section: Introductionmentioning

confidence: 99%

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A Different Technique to Create a ‘Myelomeningocele-Like’ Defect in the Fetal Rabbit

Pedreira¹,

Valente²,

Abou-Jamra³

et al. 2002

Fetal Diagn Ther

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Objective: To evaluate the fetal survival rate using a modified technique to surgically create a ‘myelomeningocele-like’ defect in a rabbit model. Methods: Six white New Zealand rabbits had a spinal defect created in their fetuses at 23 days of gestation. At 30 days of gestation, the fetuses were harvested for anatomo-pathologic evaluation. Results: The defect was created in 19 fetuses and an attempt to correct it was made in 15 cases (group I), and 4 fetuses where left without correction (group II). At 30 days, a ‘myelomeningocele-like’ defect was present in all surviving fetuses. The total survival rate was 73.68% (14/19); 11 fetus survived in group I and 3 in group II. Conclusion: The technical modifications, including fetal positioning and exposure of its back prior to the incision of the lamina, associated with a different technique for myometrium closure, offer an alternative and probably safer method to surgically create a spinal defect in the fetal rabbit.

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State of the art in translating experimental myelomeningocele research to the bedside

et al. 2021

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Myelomeningocele (MMC), the commonest type of spina bifida (SB), occurs due to abnormal development of the neural tube and manifest as failure of the complete fusion of posterior arches of the spinal column, leading to dysplastic growth of the spinal cord and meninges. It is associated with several degrees of motor and sensory deficits below the level of the lesion, as well as skeletal deformities, bladder and bowel incontinence, and sexual dysfunction. These children might develop varying degrees of neuropsychomotor delay, partly due to the severity of the injuries that affect the nervous system before birth, partly due to the related cerebral malformations (notably hydrocephalus-which may also lead to an increase in intracranial pressure-and Chiari II deformity). Traditionally, MMC was repaired surgically just after birth; however, intrauterine correction of MMC has been shown to have several potential benefits, including better sensorimotor outcomes (since exposure to amniotic fluid and its consequent deleterious effects is shortened) and reduced rates of hydrocephalus, among others. Fetal surgery for myelomeningocele, nevertheless, would not have been made possible without the development of experimental models of this pathological condition. Hence, the aim of the current article is to provide an overview of the animal models of MMC that were used over the years and describe how this knowledge has been translated into the fetal treatment of MMC in humans.

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Initial Studies of Holmium:YAG Laser Creation of Spinal Defects in Fetal Rabbits: Model for Urologic Effects of Myelomeningocele

Cited by 7 publications

References 30 publications

Simplified correction of a meningomyelocele-like defect in the ovine fetus

Simplified correction of a meningomyelocele-like defect in the ovine fetus

A Different Technique to Create a ‘Myelomeningocele-Like’ Defect in the Fetal Rabbit

State of the art in translating experimental myelomeningocele research to the bedside

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